The Tektronix 7403N is a 65 MHz oscilloscope mainframe that takes two 7000-series vertical plug-ins and one 7000-series horizontal plug-in. It has a large CRT (8 × 10 divisions @ 1.22 cm each, 154-0640-xx or 154-0672-xx tubes). There is no readout system.
The 7403N was discontinued around 1975, having been superseded largely by the popular 7603 introduced in 1973.
The 7403N consumes a maximum of 130 watts and uses convection cooling, no fan. It weighs 30 pounds.
The power supply is a linear design, similar to that of the 7313. The vertical and horizontal amplifiers are made of discrete bipolar transistors. The only integrated circuit in the vertical signal path is U214, the vertical channel switch, a 155-0022-00.
The 7403N uses a CRT anode voltage of 12 kV, produced by a solid state voltage multiplier.